The publication by A. Ishibashi: "II-VI Blue-Green Laser Diodes" in IEEE Journal of Selected Topics in Quantum Electronics, 1, 741 to 748 (1995) provides an overview of the use of II-VI semiconductor material for the production of laser diodes which emit blue or green light. ZnMgSSe, ZnCdSe or ZnSe and ZnTe is specified as the material. An MQW structure made of ZnTe/ZnSe is also mentioned. JP-A 7-66 494 and U.S. Pat. No. 5,268,918 describe beryllium-containing semiconductor compositions for the production of laser diodes emitting blue or green. U.S. Pat. No. 5,422,902 and the publications by P.M. Mensz: "BeTe/ZnSe graded band gap obmic contacts to p-ZnSe" in Appl. Phys. Lett. 64, 2148 to 2150 (1994) and by R. G. Dandrea et al.: "Design of ohmic contacts to p-ZnSe" in Appl. Phys. Lett. 64, 2145 to 2147 (1994) describe the use of a graded sequence of layers of BeTe and ZnSe for the production of contact layers between an active layer and a metallic connection contact.
The structures and materials described in the publications cited have a variety of disadvantages which have an adverse effect on the use for laser diodes. The difficulties arising when using ZnSe are that the growth of such layers on a GaAs substrate is disturbed, that a poor transport of charge carriers takes place via the interface between the II-VI semiconductor and the III-V semiconductor, and that good lattice matching of ZnTe to GaAs is not possible, for example, owing to the difference in the lattice constants. In addition, good ohmic contact to metals cannot be produced on ZnSe having p-conducting doping.